Unintended Consequences

I was going through my bookshelves and saw that I have a hardcover copy of John Ross' Unintended Consequences. It is a fifth printing, First Edition copy in hardback. The dust jacket is missing, but it is in otherwise great condition. The only real flaw is where the used bookstore I bought it from wrote the price of $26.00 on the inside of the front cover in pencil. I must have bought this book at least 10 years ago, although I don't remember when.

I am not sure what it is worth, but the cheapest ones that Amazon has are over $200 each. I would like to read it again, but I don't want to devalue it by damaging it. I had no idea they were so collectible.